[mkgmap-dev] overview2 branch -- sea not rendered at resolution 12

Wed May 8 17:53:31 BST 2013

well, I use 12, it makes the map smaller and faster --
for the overview map however - theese are the max usable numbers. So 
either skip this filter for all polygons created by the sea generator 
for the overview map (that would be a good solution), or reduce the 
filter value by resolution with the values I posted below.

I think either is fine
(also skip the filter in general for the sea generator).

also a value of 8 as by default - will as you can see - not work for 
resolution 12... (and I'm not sure if it will still work 100% for 
resolution 13 - could be that it already drops some polygons at that 
resolution).
On 08.05.2013 11:35, GerdP wrote:
> Hi Felix,
>
> quite a few numbers, I am not srure how to handle your results.
> The current processing in mkgmap is this:
> the min-size-polygon value is multiplied by 2 ^(24-resolution), e.g. a value
> of 8 will give 32 on resolution 22. This value is compared with the width
> and height of the polygon in map units. If both values are smaller, the
> object is dropped.
> I am not sure why one wants a rather large value, I guess it makes the img
> size smaller. The default
> value is 8.
> A possible solution could be to skip this filter for all polygons created by
> the SeaGenerator.
>
> Gerd
>
>
> Felix Hartmann-2 wrote
>> No, they are already missing.
>> ---Changing --min-size-polygon=12 to --min-size-polygon=1 and they
>> appear. I think the problem is the size of the sea tiles as they are cut
>> down into smaller polygons by mkgmap itself - because in the input data
>> they are big enough... However therefore I tried around all min-sizes
>> regarding the resolution to see what works!
>>
>> So here is a list of the biggest min-size-polygon usable currently:
>> 1=good for resolution 10...
>> 2=good for resolution 11, variable output on resolution 10
>> 3=good for resolution 12, variable output on resolution 11
>> 4=good for resolution 12, nearly no output on resolution 11
>> 5=good for resolution 13, variable output on resolution 12, no more
>> output on resolution 11.
>> 6=good for resolution 13, variable output on resolution 12
>> 7=good for resolution 13, variable output on resolution 12
>> 8=good for resolution 13, nearly no output on resolution 12
>> 9=good for resolution 14, variable output on resolution 13
>> 10=good for resolution 14, variable output on resolution 13
>> 11=good for resolution 14, variable output on resolution 13, no more
>> output on resolution 12..
>> 12=good for resolution 14, variable output on resolution 13, no more
>> output on resolution 12..
>>
>>
>> The strange thing about this is, that the sea in the input data is large
>> enough - I think the problem happens when splitting for subdivisions...
>>
>> Overview2 branch - before multiple level overview map --
>> min-size-polygon=12 was fine. GpsMapedit says the resolution is 13. I
>> assume the min-size was not respected because the input data just got
>> carried forward from the last level in the maps - (and
>> --min-size-polygon=12 worked fine for resolution 14!)?
>> In that case mkgmap overview2 should take the following min-sizes - no
>> matter what is actually defined:
>>
>> max min-size by resolution:
>> 1- resolution 10 or lower (10 is working still in Mapsource, dunno about
>> 9 or lower - I think not)
>> 2- resolution 11
>> 3- resolution 12
>> 6- resolution 13
>> 12- resolution 14
>> 24- resolution 15
>> 48- resolution 16
>> 96- resolution 17
>> 192-resolution 18
>> ..... don't think anything that high makes sense, but better continue
>> upwards so it causes no problems. As the results are not really
>> consistent - I would rather take 3 for resolution 12, and not 4 - as
>> maybe closer/further away from the equator results may differ a bit!
>> Theese values above, are definitely safe - I never saw missing see
>> anywhere worldwide while using- min-size-polygon=12 at resolution 14...
>>
>>
>>
>> On 08.05.2013 07:51, GerdP wrote:
>>> Hi Felix,
>>>
>>> do you see the see in the ovm_*.img files? If yes, the problem is in the
>>> part that reads back these files.
>>>
>>> Gerd
>>>
>>>
>>> Felix Hartmann-2 wrote
>>>> On 08.05.2013 02:15, Gerd Petermann wrote:
>>>>> Hi all,
>>>>>
>>>>>> Well, I first thought it would be a Mapsource/Basecamp bug, but
>>>>> actually
>>>>>> mkgmap overview2 is not rendering the sea tiles down to resolution 12.
>>>>>> The lowest resolution working is resolution 14... -- at 13 some sea is
>>>>>> rendered, at 12 no sea at all is rendered. I think unlike in my
>>>>>> earlier
>>>>>> reply to Henning - that this is some internal bug (maybe related to
>>>>> that
>>>>>> before 13 was the resolution of the overview map)
>>>>> I assume the polygons generated by SeaGenerator are too small, means,
>>>>> they are all filtered
>>>>> in the low resolution levels. Maybe we can implement a merge-polygons
>>>>> function to solve this
>>>>> problem. Anyway, this is probably not directly related to the overview
>>>>> stuff.
>>>> that's what I first thought too. But then I looked at a map created with
>>>> the same settings using the old overview2 branch (before multiple
>>>> levels) - which was done at resolution 13. And there no sea at all was
>>>> missing - while now at 13 it is mostly gone. So I guessed that there
>>>> must be some other problem...
>>>>>> Else I really think that the branch can be merged. It is really
>>>>>> working
>>>>>> well now... - and I played around a lot with it.
>>>>> :-)
>>>>> Please post a diff for the default style (or a zip file containing all
>>>>> files). I do not fully
>>>>> understand the changes.
>>>>>
>>>>>> Only other thing is maybe to have an option to delete / not delete the
>>>>>> ovm*.img files after creation.
>>>>> Yes, I think an option is ok. I prefer to have the files as it helps
>>>>> debugging.
>>>>>
>>>>>> Resolution 12 is great for continent maps like Europe (not fully
>>>>>> needed
>>>>>> - 14 could do), or Asia (13 is a must, 12 would be much better).
>>>>> Please place that knowledge as a comment in the style options file.
>>>>> Maybe you can also add something to the doc files?
>>>>>
>>>>> Gerd
>>>>>
>>>>>
>>>>>
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